A body fluid absorbent article normally includes a liquid permeable surface layer provided on a side in contact with a body skin, a leak-proof layer provided on a side farther from the body skin, and a body fluid absorbent portion provided between the surface layer and the leak-proof layer.
In this case, various compositions are known as a composition of the body fluid absorbent portion. The body fluid absorbent portion mainly consists of an absorbent material such as a super absorbent polymer, flocculent pulp (flap pulp), or crape paper. Following recent advancement of a super absorbent polymer technique, it is possible to form a thinner body fluid absorbent portion. Body fitting performance of the absorbent portion of the product is, therefore, improved and leakage of a body fluid is reduced accordingly.
The improved absorbing performance, in turn, causes consumers to demand developing a new product that is thin but high in absorbing capacity and that can be used for a long time.
To meet this demand, the body fluid absorbent portion is required to absorb a large amount of urine, for example, excreted many times. Nevertheless, whenever urination repeatedly occurs, an absorption speed of the body fluid absorbent portion is decreased, with the result the body fluid cannot be often absorbed by the body fluid absorbent portion, particularly longitudinal ends thereof. Reasons for this are considered as follows. Diffusion of the body fluid in a longitudinal direction (of the product) is slow or insufficient and a phenomenon so-called “gel blocking” occurs that the super absorbent polymer so swells as to inhibit liquid diffusion and wetting of the super absorbent polymer.
To solve these phenomena, a technique for assisting in wetting and diffusion in the longitudinal direction, a technique for preventing the gel blocking of the super absorbent polymer, an attempt to improve a form and incorporation of the super absorbent polymer, a method for securing a space in which an absorbent material swells by wetting, and the like have been proposed as disclosed in, for example, Patent Koho (Japanese Unexamined Patent Publication of Translated Version) Nos. 2000-510031 and 2000-510033.
However, none of these methods find satisfactory solutions to these disadvantages. When these causes are considered again, it is found that the body fluid absorbent portion of the conventional body fluid absorbent article is elongated and arranged in the longitudinal direction of the product on the premise that the body fluid from a discharge region wets and spreads (diffuses) up to the longitudinal ends of the portion. Therefore, as long as the diffusion of the body fluid in the longitudinal direction is insufficient, the entire body fluid absorbent portion is substantially incapable of absorbing the body fluid.
On the other hand, taking into account that there is a limit to the diffusion of the body fluid within the body fluid absorbent portion, the inventors of the present invention have proposed various body fluid absorbent articles each configured so that an absorbent material portion corresponding to a body fluid receiving portion is updated by allowing shrinkage and movement of the absorbent material when the absorbent material contacts with the body fluid, and improved techniques therefor so as to solve these disadvantages. Specifically, examples of these include a proposal disclosed in International Publication PCT/JP02/00833 filed by the applicant of the present invention.
According to this conventional technique, it is possible to provide a body fluid absorbent article that can make effective use of an entire absorbent or, more generally, a body fluid absorbent article that is high in absorbing capacity, that can sufficiently absorb the body fluid a plurality of times, and that can eventually ensure a long-time use.
This conventional technique, however, still leaves rooms for improvements in use of the absorbent material in a wider range for absorption and efficient movement of the absorbent.